Malic acid diester surfactants

ABSTRACT

This invention provides water-based compositions, particularly coating, ink, fountain solution, adhesive and agricultural compositions, manifesting reduced equilibrium and dynamic surface tension by the incorporation of a surface tension reducing amount of certain malate diester compounds of the structurewhere R1 and R2 are C3 to C6 alkyl groups.

FIELD OF THE INVENTION

The invention relates to the use of malic acid diesters to reduce thesurface tension in water-based systems.

BACKGROUND OF THE INVENTION

The ability to reduce the surface tension of water is of greatimportance in waterborne coatings, inks, adhesives, fountain solutionsand agricultural formulations because decreased surface tensiontranslates to enhanced substrate wetting in actual formulations. Surfacetension reduction in water-based systems is generally achieved throughthe addition of surfactants. Performance attributes resulting from theaddition of surfactants include enhanced surface coverage, fewerdefects, and more uniform distribution. Equilibrium surface tensionperformance is important when the system is at rest. However, theability to reduce surface tension under dynamic conditions is of greatimportance in applications where high surface creation rates areutilized. Such applications include spraying, rolling and brushing ofcoatings or spraying of agricultural formulations, or high speed gravureor ink-jet printing. Dynamic surface tension is a fundamental quantitywhich provides a measure of the ability of a surfactant to reducesurface tension and provide wetting under such high speed applicationconditions.

Traditional nonionic surfactants such as alkylphenol or alcoholethoxylates, and ethylene oxide (EO)/propylene oxide (PO) copolymershave excellent equilibrium surface tension performance but are generallycharacterized as having poor dynamic surface tension reduction. Incontrast, certain anionic surfactants such as sodium dialkylsulfosuccinates can provide good dynamic results, but these are veryfoamy and impart water sensitivity to the finished coating.

In addition to the development of high-performance surfactants, there isconsiderable interest in the industry in surfactants with improvedenvironmental characteristics. Environmental concerns have led to anincreased use of environmentally compatible surfactants as alternativeshave become available. In addition, the use of less favorable products,such as alkylphenol ethoxylate (APE) surfactants, has declined. This is,in part, due to the poor environmental characteristics of APEsurfactants, such as incomplete biodegradation and a suspicion that theymay function as endocrine mimics. The demand for high-performance,eco-friendly surfactants has stimulated efforts in new surfactantdevelopment. From this work a new family of surfactants, referred to asalkyl polyglycoside (APG) surfactants, has emerged as a readilybiodegradable, environmentally-friendly alternative to conventionalsurfactants. These materials, however, can be foamy and thus, are notsuitable for a variety of coating, ink, adhesive and agriculturalapplications where the generation of foam is undesirable. Moreover, manyAPG surfactants possess poor color characteristics and are solids orpastes. This latter property complicates handling and necessitates theformation of blends which contain significantly less than 100% activeingredient. Thus, not only is it desirable to obtain surfactants whichexhibit excellent surface tension reducing capabilities and low foamunder dynamic application conditions, but it is also highly desirablethat such new surfactants are environmentally-friendly, are liquids andpossess little or no color.

There is a need for surfactants which exhibit good equilibrium anddynamic surface tension properties, are low-foaming, are low viscosityliquids to facilitate handling, have low color and low odorcharacteristics and would be widely accepted in the waterborne coating,ink, adhesive, fountain solution and agricultural formulationindustries. Moreover, since there is substantial interest in thedevelopment of environmentally-friendly surfactants, an essentialattribute would be that these surfactants not only possess theaforementioned desired performance attributes but also are derived fromnaturally occurring compounds or their synthetic equivalents or possessfavorable biodegradation and toxicity properties.

The importance of reducing equilibrium and dynamic surface tension inapplications such as coatings, inks, adhesives, fountain solutions andagricultural formulations is well-appreciated in the art.

Low dynamic surface tension is of great importance in the application ofwaterborne coatings. In an article, Schwartz, J. “The Importance of LowDynamic Surface Tension in Waterborne Coatings”, Journal of CoatingsTechnology, September 1992, there is a discussion of surface tensionproperties in waterborne coatings and a discussion of dynamic surfacetension in such coatings. Equilibrium and dynamic surface tension wereevaluated for several surface active agents. It is pointed out that lowdynamic surface tension is an important factor in achieving superiorfilm formation in waterborne coatings. Dynamic coating applicationmethods require surfactants with low dynamic surface tensions in orderto prevent defects such as retraction, craters, and foam.

Efficient application of agricultural products is also highly dependenton the dynamic surface tension properties of the formulation. In anarticle, Wirth, W.; Storp, S.; Jacobsen, W. “Mechanisms Controlling LeafRetention of Agricultural Spray Solutions”; Pestic. Sci. 1991, 33,411-420, the relationship between the dynamic surface tension ofagricultural formulations and the ability of these formulations to beretained on a leaf was studied. These workers observed a goodcorrelation between retention values and dynamic surface tension, withmore effective retention of formulations exhibiting low dynamic surfacetension.

Low dynamic surface tension is also important in high-speed printing asdiscussed in the article “Using Surfactants to Formulate VOC CompliantWaterbased Inks”, Medina, S. W.; Sutovich, M. N. Am. Ink Maker 1994, 72(2), 32-38. In this article, it is stated that equilibrium surfacetensions (ESTs) are pertinent only to ink systems at rest. EST values,however, are not good indicators of performance in the dynamic, highspeed printing environment under which the ink is used. Dynamic surfacetension is a more appropriate property. This dynamic measurement is anindicator of the ability of the surfactant to migrate to a newly createdink/substrate interface to provide wetting during high speed printing.

U.S. Pat. No. 5,098,478 discloses water-based ink compositionscomprising water, a pigment, a nonionic surfactant and a solubilizingagent for the nonionic surfactant. Dynamic surface tension in inkcompositions for publication gravure printing must be reduced to a levelof about 25 to 40 dynes/cm to assure that printability problems will notbe encountered.

U.S. Pat. No. 5,562,762 discloses an aqueous jet ink of water, dissolveddyes and a tertiary amine having two polyethoxylate substituents andthat low dynamic surface tension is important in ink jet printing.

A variety of esters of malic acid (2-hydroxy-butanedioic acid), alsocalled malates, are known. Malic acid itself is used primarily as anadditive in beverages, candy and food. The commercial form (DL-malicacid) is produced from maleic anhydride and is classified as GRAS(Generally Recognized As Safe) by the U.S. Food and Drug Administration.In addition, the naturally occurring form (L-malic acid) is found inmany fruits at low concentrations. DE 3 011 645 A1 discloses the use ofmixed esters of hydroxycarboxylic acids as dispersion aids for theaqueous suspension polymerization of vinyl chloride. U.S. Pat. No.3,927,073 discloses esters of dicarboxylic acids with polyhydroxytertiary mines as both a detergent and a fabric softening agent.

DE 19 621 681 Al discloses aqueous pearl luster concentrates comprisingesters of polyvalent carboxylic acids and/or hydroxycarboxylic acidswith fatty alcohols in conjunction with emulsifiers and polyols. Themono- or di-esters of C6 to C22 alcohols were used to impart a pearlluster to “surface active agents” for use in hair shampoo and manualdishwashing detergents. Among the suggested acids is malic acid.

U.S. Pat. No. 5,695,679 discloses dishwashing detergent formulationscomprising esters of mono- or polycarboxylic acids and mono- orpolyhydric alcohols as “organic silver coating agents”. Malic acid islisted among the carboxylic acids.

U.S. Pat. No. 2,925,352 discloses derivatives of malic acids asplasticisers for water-insoluble thermoplastic organic film-formingpolymers. Example 4 shows a film-forming dope comprising 100 partscellulose acetate, 12.5 parts of diisobutyl malate, 400 parts ofdioxalane and 27 parts water.

U.S. Pat. No. 2,122,716 discloses hydroxycarboxylic acid esters ofC10-C14 alcohols.

C. D. Vaughan and D. A. Rice, J. Dispersion Science and Technology,1990, 11, 83, show the use of dioctylmalate in an oil-in-water emulsionused to test an equation for the “Required HLB” value for the oil phasein order to obtain a stable emulsion.

Kyotani et al, Sekiyu Gakkaishi, 1988, 31, 382, studied the effect of OHgroups on the flow behavior of mono- and di-ester lubricants made from2-ethylhexanol. The increased viscosity of di(2-ethylhexyl)malate versusdi(2-ethylhexyl)succinate illustrates that the latter is a betterlubricant. In this case, all liquids were studied neat and not inaqueous media.

U.S. Pat. No. 4,005,189 discloses as a deodorant an ester of analiphatic mono- or dihydroxycarboxylic acid or an aliphatic mono- ordihydroxy-dicarboxylic acid having 2 to 4 carbons with an aliphaticalcohol having 1 to 6 carbons. Diethyl malate, diisopropyl malate anddihexyl malate are shown.

EP 0 850 935 A2 discloses concentrated solutions of 1,3,5-triazinederivatives and certain esters of carboxylic acids as solvents. Apreferred solvent is bis(2-ethyl-hexyl) malate.

U.S. Pat. No. 5,505,937 discloses a transfer resistant cosmeticcomposition containing as a low viscosity oil dioctyl malate among themany listed esters.

U.S. Pat. No. 5,702,693 discloses an aqueous liquid composition forremoval of gypsum from the skin of a patient comprising a water-miscibleorganic solvent, an acid and an emollient. The examples show dioctylmalate as an emollient.

U.S. Pat. No. 5,597,576 discloses oil-based transparent gels, i.e.,“lipogels”, containing malic acid diesters of C12-13 single-branch fattyalcohols.

SUMMARY OF THE INVENTION

This invention provides water-based compositions containing an organicor inorganic compound, particularly aqueous organic coating, ink,adhesive, fountain solution and agricultural compositions, havingreduced equilibrium and dynamic surface tension by incorporation of aneffective amount of a diester of malic acid of the following structure:

where R₁ and R₂ are C3 to C6 alkyl groups, but preferably R₁ and R₂ arethe same. It is desirable that an aqueous solution of the malate diesterdemonstrates a dynamic surface tension of less than 45 dynes/cm at aconcentration of ≦5 wt % in water at 25° C. and 6 bubble/secondaccording to the maximum-bubble pressure method. Themaximum-bubble-pressure method of measuring surface tension is describedin Langmuir 1986, 2, 428-432, which is incorporated by reference.

By “water-based”, “aqueous” or “aqueous medium”, we mean, for purposesof this invention, a solvent or liquid dispersing medium which comprisesat least 90 wt %, preferably at least 95 wt %, water. Obviously, an allwater medium is also included.

Also provided is a method for lowering the equilibrium and dynamicsurface tension of such aqueous compositions by the incorporation ofthese malate diester compounds.

Also provided is a method for applying a coating of a water-basedinorganic or organic compound-containing composition to a surface topartially or fully coat the surface with the water-based composition,the composition containing an effective amount of a malate diestercompound of the above structure for reducing the dynamic surface tensionof the water-based composition.

There are significant advantages associated with the use of these malatediesters in water-based organic coatings, inks, adhesives, fountainsolutions and agricultural compositions and these advantages include:

water-borne coatings, inks, adhesives, fountain solutions andagricultural compositions which may be applied to a variety ofsubstrates with excellent wetting of substrate surfaces includingcontaminated and low energy surfaces;

a reduction in coating or printing defects such as orange peel andflow/leveling deficiencies;

coating and ink compositions capable of high speed application;

low-foam surfactants capable of reducing dynamic surface tension;

low-foam surfactants which are low viscosity liquids at room temperaturefor facile handling;

low-foam surfactants which have low odor and color;

water-borne coatings and inks which have low volatile organic content,thus making these formulations environmentally favorable;

water-borne compositions using a surfactant derived from natural acidsor synthetic equivalents, thus making such compositions environmentallyfavorable; and

low-foam surfactants which exhibit good biodegradation characteristicsand thus, are environmentally favorable.

Because of their excellent surfactant properties and the ability tocontrol foam, these materials are likely to find use in manyapplications in which reduction in dynamic and equilibrium surfacetension and low foam are important. Applications in which low foam isimportant include various wet-processing textile operations, such asdyeing of fibers, fiber souring, and kier boiling, where low-foamingproperties would be particularly advantageous; they may also haveapplicability in soaps, water-based perfumes, shampoos, and variousdetergents where their marked ability to lower surface tension whilesimultaneously producing substantially no foam would be highlydesirable.

DETAILED DESCRIPTION OF THE INVENTION

This invention relates to the use of compounds of the structure

where R₁ and R₂ are independently a C3-C6 alkyl group, preferably R₁=R₂,for the reduction of equilibrium and dynamic surface tension inwater-based compositions containing an organic compound, particularlycoating, ink, fountain solution, adhesive and agricultural compositionscontaining organic compounds such as polymeric resins, herbicides,fungicides, insecticides or plant growth modifying agents. It isdesirable that an aqueous solution of the malate diester demonstrates adynamic surface tension of less than 45 dynes/cm at a concentration of≦5 wt % in water at 25° C. and 6 bubble/second according to themaximum-bubble-pressure method. The maximum-bubble-pressure method ofmeasuring surface tension is described in Langmuir 1986, 2, 428-432,which is incorporated by reference.

In one aspect of the invention the malate diesters of the above formuladisplay excellent ability to reduce equilibrium and dynamic surfacetension while producing substantially no foam.

These materials may be prepared by esterification of malic acid with analcohol. The reaction is illustrated below:

For the purpose of this invention all stereoisomers of malic acid aresuitable, including L-malic acid, D-malic acid and DL-malic acid.

The esterification reaction may be performed using many catalysts andprocesses as described in the Kirk-Othmer Encyclopedia of ChemicalTechnology, 4^(th) Ed., Vol. 9, p. 755-780, which is incorporated byreference. The reaction is preferentially catalyzed by an acid. Examplesof suitable acid catalysts are acidic ion exchange resins (i.e.Amberlyst® 15 resin), p-toluenesulfonic acid, boron trifluoride etherateand mineral acid catalysts, such as hydrochloric acid and sulfuric acid.In addition, the esterification reaction may be driven by removal of thewater by-product. In this case, the water may be removed as anazeotrope, typically with the alcohol used in the reaction. Othersuitable methods to remove water include the use of a drying agent.Also, solvents may be added to the reaction to aid the dissolution ofmalic acid or to facilitate azeotropic removal of water.

All alcohols or mixtures of alcohols containing the requisite C3 to C6alkyl substituents may be utilized for the preparation of thedialkylmalates of this invention with alcohols containing a 3-5 carbonsbeing preferred and those containing 4 carbons being especiallypreferred. Alkyl groups which are suitable should have sufficient carbonto confer surface activity (i.e. an ability to reduce the surfacetension of water) to the material but not enough carbon to decrease thesolubility to the extent that the ability of the material to reducesurface tension is insufficient for a particular application. Ingeneral, an increase in the carbon number increases the efficiency ofthe resulting dialkylmalate (i.e. less surfactant is required to obtaina given decrease in surface tension), but decreases its ability toreduce surface tension at high surface creation rates. The latter effectis a result of the fact that increased carbon number generally decreasesthe water solubility of the material, and consequently, diminishes thediffusive flux of surfactant to newly-created surface. Generally, in thepractice of this invention, it is desirable to choose alkyl groups suchthat the resulting dialkylmalates have a solubility limit in water from0.005 to 5 wt %, preferably from 0.01 to 3 wt %, and most preferablyfrom 0.1 to 1.0 wt %.

The alkyl groups in the malates of this invention may be the same ordifferent. However, symmetrical malates are preferred due to ease insynthesis. Alkyl groups may be linear or branched, with alkyl groupscontaining terminal branching being preferred. The point of attachmentto the oxygen may be on either an internal or terminal carbon, with aterminal carbon being preferred. The total number of carbons on R₁ andR₂ should be ≦6; fewer than this diminishes the surface activity of thedialkylmalate too greatly. The total number of carbons should be ≦12; agreater number decreases the solubility of the material to such a degreethat its use in many formulations is impractical. Examples of suitablealkyl groups are n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl,n-pentyl, 2-pentyl, 3-pentyl, isopentyl, neopentyl, cyclopentyl,2-methylbutyl, 3-methyl-2-butyl, n-hexyl, 2-hexyl, 3-hexyl, cyclohexyl,2-ethylbutyl, 4-methyl-2-pentyl and so on. Preferred derivatives arethose in which R₁=R₂ and contain a total of 6 to 12 alkyl carbons. Ofthese derivatives those which contain 6 to 10 alkyl carbons arepreferred and those containing 8 to 10 alkyl carbons especiallypreferred, with those containing 8 alkyl carbons being the mostpreferred, especially in the case where R₁=R₂=isobutyl. Moreover, thosealkyl groups which contain terminal branching or attachment at terminaloxygen are preferred.

An amount of dialkylmalate compound that is effective to reduce theequilibrium and/or dynamic surface tension of the water-based, organiccompound-containing composition is added. Such effective amount mayrange from 0.001 to 20 wt %, preferably 0.01 to 10 wt %, and mostpreferably 0.05 to 5 wt %, of the aqueous composition. Naturally, themost effective amount will depend on the particular application and thesolubility of the dialkylmalate.

The malate diesters are suitable for use in an aqueous compositioncomprising in water an inorganic compound which is a mineral ore or apigment or an organic compound which is a pigment, a polymerizablemonomer, such as addition, condensation and vinyl monomers, anoligomeric resin, a polymeric resin, a detergent, a caustic cleaningagent, a herbicide, a fungicide, an insecticide, or a plant growthmodifying agent.

In the following water-based organic coating, ink, adhesive, fountainsolution and agricultural compositions containing a dialkylmalateaccording to the invention, the other listed components of suchcompositions are those materials well known to the workers in therelevant art.

A typical water-based protective or decorative organic coatingcomposition to which the malate diester surfactants of the invention maybe added would comprise in an aqueous medium 30 to 80 wt % of a coatingcomposition containing the following components:

Water-Based Organic Coating Composition 0 to 50 wt % PigmentDispersant/Grind Resin 0 to 80 wt % Coloring Pigments/ExtenderPigments/Anti-Corrosive Pigments/Other Pigment Types 5 to 99.9 wt %Water-Borne/Water-Dispersible/Water-Soluble Resins 0 to 30 wt % SlipAdditives/Antimicrobials/Processing Aids/ Defoamers 0 to 50 wt %Coalescing or Other Solvent 0.01 to 10 wt % Surfactant/WettingAgent/Flow and Leveling Agents 0.01 to 20 wt % Dialkylmalate

A typical water-based ink composition to which the malate diestersurfactants of the invention may be added would comprise in an aqueousmedium 20 to 60 wt % of an ink composition containing the followingcomponents:

Water-Based Ink Composition 1 to 50 wt % Pigment 0 to 50 wt % PigmentDispersant/Grind Resin 0 to 50 wt % Clay base in appropriate resinsolution vehicle 5 to 99.9 wt %Water-Borne/Water-Dispersible/Water-Soluble Resins 0 to 30 wt %Coalescing or Other Solvent 0.01 to 10 wt % Surfactant/Wetting Agent0.01 to 10 wt % Processing Aids/Defoamers/Solubilizing Agents 0.01 to 20wt % Dialkylmalate

A typical water-based agricultural composition to which the malatediester surfactants of the invention may be added would comprise in anaqueous medium 0.1 to 80 wt % of an agricultural composition containingthe following components:

Water-Based Agricultural Cornposition 0.1 to 50 wt % Pesticide,Insecticide, Herbicide or Plant Growth Modifying Agent 0.01 to 10 wt %Surfactant 0 to 5 wt % Dyes 0 to 20 wt %Thickeners/Stabilizers/Co-surfactants/Gel Inhibitors/ Defoamers 0 to 25wt % Antifreeze 0.01 to 50 wt % Dialkylmalate

A typical water-based fountain solution composition would the followingcomponents:

Water-Based Fountain Solution 0.05 to 10 wt % Film formable, watersoluble macromolecule 1 to 25 wt % Alcohol, glycol, or polyol with 2-12carbon atoms, water soluble or can be made to be water soluble 0.01 to20 wt % Water soluble organic acid, inorganic acid, or a salt thereof 30to 70 wt % Water 0.01 to 5 wt % Dialkylmalate

A typical water-based adhesive composition to which the dialkylmalatesurfactants of the invention may be added would comprise in an aqueousmedium 30 to 65 wt % of an adhesive composition containing the followingcomponents:

Water-Based Adhesive 50 to 99 wt % Polymeric Resin (SBR, VAE, Acrylic) 0 to 50 wt % Tackifier  0 to 0.5 wt % Defoamer  0.5 to 2 wt %Dialkylmalate

With the exception of diisopropyl-(S)-(−)-malate and dibutyl-DL-malate,which were available commercially, all malates in the following exampleswere synthesized and characterized via Gas Chromatography/MassSpectrometry (GC/MS) and Nuclear Magnetic Resonance (NMR) spectroscopy.All dialkylmalates prepared ranged from >96% to >99% pure.

EXAMPLE 1

Diisopropyl-(S)-(−)-malate was purchased from Aldrich Chemical Company(99%) and used as received. The compound was a low viscosity, clear,colorless liquid with no detectable odor.

EXAMPLE 2

Dibutyl-DL-malate was purchased from TCI America (99%) and used asreceived. The compound was a low viscosity, clear, colorless liquid witha slight, pleasant odor.

EXAMPLE 3

Diisobutyl-DL-malate was prepared by esterification of DL-malic acidwith isobutyl alcohol. To a three-neck 1 L round-bottomed flask equippedwith a reflux condenser, Dean-Stark trap, septum, thermocouple andmechanical stirrer, were added DL-malic acid (75.91 g),2-methyl-1-propanol (210 mL) and Amberlyst® 15 ion exchange resin (10g). The mixture was placed under nitrogen and heated to reflux. At 106°C., two phases started to collect in the Dean-Stark trap. The reactiontemperature was maintained at 108° C. for 2 hr 15 min and the water wascontinuously removed via the Dean-Stark trap. As collection in theDean-Stark trap slowed, the reaction temperature was increased to 115°C. and fresh alcohol (50 mL) was added to the reaction. The reaction washeated to 120° C. and more alcohol (50 mL) was added. At this point, nomore water collected in the Dean-Stark trap. The product was separatedfrom the catalyst via filtration. The crude yellow liquid was purifiedvia vacuum distillation. Diisobutyl-DL-malate was obtained as a lowviscosity, clear, colorless liquid with a slight pleasant odor (120.4 g,86.3% yield).

EXAMPLE 4

Di-sec-butyl-DL-malate was prepared using a procedure similar to Example3. This compound was isolated as a bottoms product. To the reactionflask, DL-malic acid (80.23 g), 2-butanol (220 mL) and Amberlyst® 15 ionexchange resin (11.2 g) were added. The mixture was placed undernitrogen and heated to reflux. At 102° C., one phase started to collectin the Dean-Stark trap. The reaction was maintained at 102° C. for 4 hr.During this time, the water/alcohol azeotrope was removed as freshalcohol was added. The product was dissolved in diethyl ether, separatedfrom the catalyst via filtration over a bed of silica, washed withsaturated sodium bicarbonate a number of times, washed once with water,and dried over magnesium sulfate. Diethyl ether was removed via rotaryevaporation. Di-sec-butyl-DL-malate was obtained as a low viscosity,clear light yellow liquid with no detectable odor (46 g, 31% yield)after pumping on the sample in vacuo to remove residual 2-butanol.

EXAMPLE 5

Dipentyl-DL-malate was prepared using a procedure similar to that inExample 4.

To the reaction flask, DL-malic acid (100.43 g), 1-pentanol (325 mL) andAmberlyst® 15 ion exchange resin (14.2 g) were added. The mixture wasplaced under nitrogen and heated to reflux. At 108° C., two phasesstarted to collect in the Dean-Stark trap. The reaction was maintainedat 110-120° C. for 4 hr 15 min and water was continuously removed. Theproduct was separated from the catalyst via filtration over silica using300 mL diethyl ether. The organic layer was washed 4 times withsaturated sodium bicarbonate, washed once with water, and dried overmagnesium sulfate. Diethyl ether was removed via rotary evaporation.Dipentyl-DL-malate was obtained as a low viscosity, slightly hazy, verylight yellow liquid with a slight pleasant odor (116.5 g, 55.6% yield)after pumping on the sample in vacuo to remove residual 1-pentanol.

EXAMPLE 6

Diisoamyl-DL-malate was prepared using a procedure similar to that inExample 4. To the reaction flask, DL-malic acid (87.54 g),3-methyl-1-butanol (285 mL) and Amberlyst® 15 ion exchange resin (11.9)were added. The mixture was placed under nitrogen and heated to reflux.At 109° C., two phases started to collect in the Dean-Stark trap. Thereaction was maintained at 110° C. for 8 hr, during this time water wascontinuously removed. The product was dissolved in diethyl ether andseparated from the catalyst via filtration over a bed of silica. Theorganic layer was washed with saturated sodium bicarbonate a number oftimes, washed once with water, and dried over magnesium sulfate. Diethylether was removed via rotary evaporation. Diisoamyl-DL-malate wasobtained as a low viscosity, clear colorless liquid with a slight odor(130 g, 72% yield) after pumping on the sample in vacuo to removeresidual 3-methyl-1-butanol.

EXAMPLE 7

Di(2-methylbutyl)-DL-malate was prepared using a procedure similar tothat in Example 4. To the reaction flask, DL-malic acid (100.56 g),2-methyl-1-butanol (325 mL) and Amberlyst® 15 ion exchange resin (15.1g) were added. The mixture was placed under nitrogen and heated toreflux. At 108° C., two phases started to collect in the Dean-Starktrap. After 1.5 hr, the reaction temperature was increased to 115° C.for 20 minutes and 120° C. for 20 minutes. Once water ceased to collectin the Dean-Stark trap, the product was diluted with diethyl ether,collected via filtration over a short bed of silica, washed 4 times withsaturated sodium bicarbonate, once with water and dried over magnesiumsulfate. The diethyl ether was removed via rotary evaporation.Di-(2-methylbutyl)-DL-malate was obtained as a low viscosity, clear,very light yellow liquid with no detectable odor (139.8 g, 68% yield)after removing residual 2-methyl-1-butanol via vacuum distillation.

EXAMPLE 8

Dihexyl-DL-malate was prepared using a procedure similar to that inExample 4 with p-toluenesulfonic acid as the catalyst. Unlike Examples3-7, the reaction was not performed in neat alcohol. In this case,1,4-dioxane was added to dissolve the starting acid. To the reactionflask, DL-malic acid (80.91 g), hexyl alcohol (307 mL), 1,4-dioxane (200mL) and p-toluenesulfonic acid (12.3 g) were added. The mixture wasplaced under nitrogen and heated to reflux. At 103° C., one phasestarted to collect in the Dean-Stark trap. The reaction temperature wasincreased to 110° C. and after 2 hr 40 min very little liquid hadcollected in the trap. The reaction temperature was increased to 115° C.and held until no more liquid collected in the trap. The product wasneutralized with saturated sodium bicarbonate, diluted with diethylether, washed three times with saturated sodium bicarbonate, once withwater and dried over magnesium sulfate. The diethyl ether was removedvia rotary evaporation. Dihexyl-DL-malate was obtained as a lowviscosity, clear, colorless liquid with a slight pleasant odor (127.7 g,70% yield) after removing residual hexyl alcohol via vacuumdistillation.

EXAMPLE 9

Di(4-methyl-2-pentyl)-DL-malate was prepared using a procedure similarto that in Example 8. To the reaction flask, DL-malic acid (90.76 g),4-methyl-2-pentanol (350 mL), 1,4-dioxane (200 mL) and p-toluenesulfonicacid (15.2 g) were added. The mixture was placed under nitrogen andheated to reflux. At 105° C., one phase started to collect in theDean-Stark trap. After 2 hr, the temperature was increased to 110° C.After 1 hr 10 min, the temperature was increased to 112° C. and helduntil no more liquid collected in the trap. The reaction product wasneutralized with saturated sodium bicarbonate, diluted with diethylether, washed three times with saturated sodium bicarbonate, once withwater and dried over magnesium sulfate. The diethyl ether was removedvia rotary evaporation. Di(4-methyl-2-pentyl)-DL-malate was obtained asa low viscosity, light yellow, slightly hazy liquid with no detectableodor (166.8 g, 81.5% yield) after removing residual 4-methyl-2-pentanolvia vacuum distillation.

EXAMPLE 10

Dibenzyl-DL-malate was prepared using the method of Lee et al, J. Chem.Soc. Perkin Trans. I, 1995, 2877. To a three-neck 1 L round-bottomedflask equipped with a reflux condenser, Dean-Stark trap, thermocoupleand mechanical stirrer, were added DL-malic acid (81.96 g), benzylalcohol (132.0 g), toluene (620 mL) and p-toluene-sulfonic acid (1.165g). The mixture was placed under nitrogen and heated to reflux. At 100°C., two phases started to collect in the Dean-Stark trap. After 2 hr,the reaction temperature was increased to 105° C. for 1.5 hr. The crudeproduct was neutralized with saturated sodium bicarbonate and pouredinto a separatory funnel. The organic layer was washed with saturatedsodium bicarbonate twice, washed once with water, and dried overmagnesium sulfate. The toluene was removed via rotary evaporation.Two-thirds of the crude product were purified via column chromatography(20% ethyl acetate in hexane eluent). Residual benzyl alcohol wasremoved via vacuum distillation to give a low viscosity, clear,colorless oil with no detectable odor (49.9 g, 28% yield).

In the following Examples dynamic surface tension data were obtained foraqueous solutions of various compounds using the maximum bubble pressuremethod at bubble rates from 0.1 bubbles/second (b/s) to 20 b/s. Thesedata provide information about the performance of a surfactant atconditions from near-equilibrium (0.1 b/s) through extremely highsurface creation rates (20 b/s). In practical terms, high bubble ratescorrespond to high printing speeds in lithographic printing, high sprayor roller velocities in coating applications, and rapid applicationrates for agricultural products.

EXAMPLES 11-20

Solutions of the materials of Examples 1-10 in distilled water wereprepared. Their dynamic surface tension was evaluated at 25° C. asdescribed above, and these data were used to determine the quantitiesprovided in the Table 1. The pC₂₀ value is defined as the negativelogarithm of the molar concentration of surfactant required to decreasethe surface tension of an aqueous solution to 52.1 dyne/cm, that is, 20dyne/cm below that of pure water when the measurement is performed at0.1 b/s. This value is a measure of the efficiency of a surfactant. Ingeneral, an increase in pC₂₀ value of 1.0 indicates that 10 times lesssurfactant will be required to observe a given effect. In addition, therelative efficiency of surfactants can be obtained by comparing surfacetension reduction of solutions containing the same amount of differentsurfactants. Such data is given for 0.1 wt % solutions of thedialkylmalates at 1.0 and 6.0 bubbles/second (b/s). The solubility limitwas determined by intersection of the linear portion of a surfacetension / In concentration curve with the limiting surface tension as isdescribed in many textbooks. The limiting surface tensions at 0.1, 1, 6and 20 b/s represent the lowest surface tensions in water which can beachieved at the given surface creation rates for a given surfactantregardless of the amount of surfactant used and is used to evaluate theeffectiveness of a surfactant. These values give information about therelative ability of a surfactant to reduce surface defects undernear-equilibrium conditions (0.1 b/s) through very dynamic conditions(20 b/s). Lower surface tensions would allow the elimination of defectsupon application of a formulation onto lower energy surfaces.

TABLE 1 Surface Tension Data for Dialkylmalates solubility limitingγ^(b) γ(0.1 wt % solution)^(c) Structure limit^(a) pC₂₀ (0.1 b/s) (1b/s) (6 b/s) (20 b/s) (1 b/s) (6 b/s) Example 11 (Example 1)

5 1.83 33.6 33.8 34.0 35.3 59.2 60.1 Example 12 (Example 2)

0.3 3.04 35.8 36.0 36.5 38.6 43.8 44.8 Example 13 (Example 3)

0.4 3.08 33.5 33.3 33.4 35.3 44.1 45.2 Example 14 (Example 4)

0.6 2.77 36.5 36.7 37.3 38.1 47.8 48.5 Example 15 (Example 5)

0.03 3.52 36.8 38.2 40.5 50.1 38.2 40.5 Example 16 (Example 6)

0.04 3.86 35.6 36.8 39.5 48.0 36.8 39.5 Example 17 (Example 7)

0.04 3.47 37.8 38.9 41.2 49.7 38.9 41.2 Example 18 (Example 8)

0.005 3.25 55.6 65.2 69.3 71.2 58.8 52.0 Example 19 (Example 9)

0.02 3.84 40.8 50.9 63.9 69.4 46.2 56.4 Example 20 (Example 10)

0.08 2.23 54.0 57.7 60.3 70.0 61.5 65.2 ^(a)Weight % ^(b)Dyne/cm^(c)Limiting γ at 0.1 wt. % surfactant. At 0.5 wt. % dihexyl-DL-malateand above a cloudy, 2-phase mixture was observed with a limiting γ of38.9 dyne/cm (0.1 b/s), 40.5 dyne/cm (1 b/s), 41.1 dyne/cm (6.0 b/s) and44.9 dyne/cm (20 b/s).

The data in Table 1 illustrate that various dialkylmalates have theability to reduce the surface tension of an aqueous composition and thatin many cases low surface tension can be maintained even underconditions in which surface is created at a rapid rate. Examples 11-20demonstrate that dialkylmalates containing alkyl groups of three to sixcarbon atoms exhibit surface tension values of less than 45 dyne/cm at aconcentration of ≦5 wt % in water at 25° C. and at 0.1 b/s. Furthermore,dialkylmalates containing alkyl groups with three to five carbon atomsdemonstrate a reduction in the dynamic surface tension of aqueoussolutions of less than 45 dyne/cm under more dynamic conditions (6 b/s)and at a concentration of ≦5 wt % in water at 25° C. In comparison, C6and greater dialkylmalates performed poorly under these conditions.Moreover, dialkylmalates containing alkyl groups with four to fivecarbon atoms can achieve dynamic surface tension reduction of aqueouscompositions of less than 42 dyne/cm at 6 b/s at a concentration of <1wt % surfactant. Surprisingly, dialkylmalates which contain C4 groupsexhibit an optimum combination of effectiveness and efficiency withsurface tension reduction of less than 40 dyne/cm at very fast surfacecreation rates (20 b/s) at a concentration of <1 wt % surfactant. Of theC4 dialkylmalates, those prepared from primary alcohols are preferred,with those containing terminal branching being the most preferred.

Overall, dialkylmalates containing C3 to C5 alkyl groups exhibitlimiting dynamic surface tension values <38 dyne/cm at low surfacecreation rates (0.1 b/s) and values <50 dyne/cm at high surface creationrates (20 b/s). Specifically, dipentyl-DL-malate, diisoamyl-DL-malateand di(2-methylbutyl)-DL-malate are very efficient at reducing dynamicsurface tension. This characteristic is evidenced by pC₂₀ values forthese compounds of 3.52, 3.86 and 3.47, respectively. Moreover, the highefficiency of dipentyl-DL-malate, diisoamyl-DL-malate anddi(2-methylbutyl)-DL-malate is evidenced by the surface tension data for0.1 wt % compositions of these surfactants which are capable ofmaintaining a surface tension <42 dyne/cm at relatively high surfacecreation rates (6 b/s). In contrast, diisopropyl-(S)-(−)-malate is avery effective, but not very efficient surfactant. Althoughdiisopropyl-(S)-(−)-malate is capable of maintaining a surface tension<34 dyne/cm at very fast rates (20 b/s), 5 wt % surfactant is requiredto reduce the surface tension to a similar value obtained for 0.1 to 0.5wt % compositions of C4 dialkylmalates (Examples 12-14) and 0.05 to 0.1wt % solutions of C5 dialkylmalates (Examples 15-17). In contrast, C4dialkylmalates provide sufficient effectiveness (i.e. reduction indynamic surface tension) with reasonable efficiencies (i.e. use levels).For example, diisobutyl-DL-malate can maintain a limiting surfacetension less than 36 dyne/cm even at the highest surface creation ratesmeasured (20 b/s). Moreover, this value covers a narrow surface tensionrange for all bubble rates and is for a 0.5 wt % solution. Thus, the C4alkyl groups have optimum carbon to confer sufficient surface activity(i.e. efficiency) to the material but not enough carbon to decrease thesolubility to the extent that the ability of the material to reducesurface tension is insufficient for a particular application (i.e.effectiveness).

In addition to the number of carbon atoms in the alkyl chain, thestructure of the alkyl chain was observed to have an unanticipatedeffect on the properties of the malic acid diester surfactants of thisinvention. Particularly, branching at the end of the alkyl chain wasfound to improve both the efficiency and effectiveness of thedialkylmalate surfactant whereas, the attachment of an oxygen atom at aninternal position on the alkyl group had a negative effect on surfactantperformance. For example, the terminal branching present indiisobutyl-DL-malate accounts for a decrease in the limiting surfacetension of 3.3 dyne/cm at 20 b/s when compared to dibutyl-DL-malate. Inaddition, the highest surface tensions exhibited for aqueouscompositions containing 0.1 wt % of a C4 dialkylmalate were observed fordi-sec-butyl-DL-malate, which was prepared from a secondary alcohol.Such differences in the performance of dialkylmalates containing thesame number of carbon atoms would not be expected from what is known inthe art. Thus, for dialkylmalates consistent with this invention, thosewith alkyl groups containing oxygen atoms attached at a terminalposition are particularly applicable, with those containing terminalbranching being preferred and with isobutyl groups being the mostpreferred for the reduction of surface tension of water in water-based,organic compound containing compositions, including waterborne coatings,inks, adhesives, fountain solutions and agricultural formulations.However, ultimately the choice of dialkylmalate will depend upon theapplication.

EXAMPLES 21-30

The foaming properties of 0.1 wt % solutions of the dialkylmalatesurfactants of this invention were examined using a procedure based uponASTM D 1173-53. In this test, a 0.1 wt % solution of the surfactant isadded from an elevated foam pipette to a foam receiver containing thesame solution. The foam height is measured at the completion of theaddition (“Initial Foam Height”) and the time required for the foam todissipate at the air-liquid interface (“Time to 0 Foam”) is recorded.This test provides a comparison between the foaming characteristics ofvarious surfactant solutions. In general, in coatings, inks, adhesives,fountain solutions and agricultural compositions, foam is undesirablebecause it complicates handling and can lead to coating and printdefects, and to inefficient application of agricultural materials. Thedata are presented in Table 2.

TABLE 2 Foam Test initial foam Structure (cm) time to zero foam Example21 (Example 1)

1.3 14 sec Example 22 (Example 2

0.9 20 sec Example 23 (Example 3)

0.6 0.2 sec Example 24 (Example 4)

1.0 1 min Example 25 (Example 5)

0.5 0.2 sec Example 26 (Example 6)

0.3 0.3 sec Example 27 (Example 7)

1.2 0.1 sec Example 28 (Example 8)

0.5 0.1 sec Example 29 (Example 9)

0 0 sec Example 30 (Example 10)

0 0 sec

As illustrated, the ability to control foam is advantageous in manyapplications, including coatings, inks, adhesives, fountain solutions,agricultural formulations, soaps, detergents, food processing and so on.The results for the malate diesters are reported in Table 2. A drawbackto the use of conventional surfactants in coatings, inks, adhesives,fountain solutions and agricultural compositions is the formation ofconsiderable quantities of long-lasting foam in these systems. For suchapplications, it is desired that a surfactant forms little foam and thatthe foam which forms dissipates quickly. The data in Table 2 show thatthe compounds of this invention form very little foam or no measurablefoam, and that the foam which forms dissipates quickly. Moreover, all ofthese materials form less initial foam and many form faster breakingfoam than the current art. Surprisingly, linear alkyl groups and thosewhich were prepared from secondary alcohols produced more initial foamand longer lasting foam than their counterparts which contain the samenumber of carbon atoms and alkyl groups with terminal branching.Therefore, malic acid diester surfactants which contain terminalbranching are preferred as low-foaming surfactants, especiallydiisobutyl-DL-malate and diisoamyl-DL-malate. Overall, in addition totheir ability to reduce the surface tension of organic-containingaqueous compositions, these materials have desirable foam propertieswith respect to their use in coatings, inks, adhesives, fountainsolutions and agricultural compositions.

EXAMPLES 31-41

The ultimate biodegradability of various dialkylmalates(diisopropyl-(S)-(−)-malate, dibutyl-DL-malate, diisobutyl-DL-malate,di-sec-butyl-DL-malate, dipentyl-DL-malate, diisoamyl-DL-malate,di-(2-methylbutyl)-DL-malate, dihexyl-DL-malate,di-(4-methyl-2-pentyl)-DL-malate and dibenzyl-DL-malate) is illustratedin Table 3. Assessment of biodegradability of these compounds was madeusing the Carbonaceous Biological Demand test at 5 days (CBOD5) and at28 days (CBOD28). The test samples were weighed out and solubilized inMilli-Q water with a target total organic carbon (TOC) content of 100mg/L. The chemical oxygen demand (COD) was measured on these solutionsas a measure of the complete oxidation or Ultimate Biological OxygenDemand (UBOD). These prepared samples were run in triplicate in 5 dayand 28 day CBOD tests using a biomass seed from a Easton, PA WastewaterTreatment Plant which was not acclimatized to the compounds of thisinvention. Each measurement (5 day and 28 day CBOD) was run three timesfor each compound to confirm reproducibility. The results from the CBODtests at 5 and 28 days were divided by the COD results for eachrespective solution and multiplied by 100 to calculate a percentbiodegradation. A glucose/glutamic acid solution, which is readilybiodegradable, was run as a positive control to check biomass health.This is the preferred control for BOD tests as listed in the StandardMethods. Examples which showed very low biodegradation which was belowthe limit of detection for the test (<24 mg/L or <8% biodegradation) arereported as 0% degraded in Table 3.

For compounds that are extremely biodegradable a high percentbiodegradation is usually seen in the CBOD5 measurement, even when usingunacclimatized biomass. Other compounds require a longer period of timeduring which the degrading organisms develop enzyme systems to utilizethe test material as a food source. For these compounds, a higher oxygendemand is seen at 28 days. Compounds with high (i.e. greater than 60%)biodegradation after 28 days may be considered easily biodegraded.

The results of these studies showed that dibutyl-DL-malate,diisobutyl-DL-malate, dipentyl-DL-malate, diisoamyl-DL-malate,di-(2-methylbutyl)-DL-malate, dihexyl-DL-malate and dibenzyl-DL-malateall exhibit significant biodegradation after only 5 days in the CBOD5test using unacclimatized biomass. Surprisingly, those dialkylmalatescontaining oxygen atoms attached at a terminal position demonstratedsignificantly more percent biodegradation than the corresponding malatescontaining an oxygen atom which was attached at an internal position onthe alkyl group. For example, diisopropyl-(S)-(−) -malate,di-sec-butyl-DL-malate and di-(4-methyl-2-pentyl)-DL-malate weredegraded only 0-3% after 5 days, whereas diisobutyl-DL-malate,diisoamyl-DL-malate and di-(2-methylbutyl)-DL-malate exhibited asignificant amount of biodegradation after only 5 days (i.e. 13-39%).

After 28 days, all malates except the highly brancheddi(4-methyl-2-pentyl)malate degraded greater than 60%. Due to the lowlevel of measured biodegradation for di(4-methyl-2-pentyl)malate, thiscompound is not preferred relative to the more biodegradable malates ofthis invention. Overall, after 28 days malates with shorter alkyl chainsdegraded more than those with longer chains. This effect may be due tothe decreasing solubility as the alkyl chain length increases. Of thelonger chain malates (i.e. greater than C5), those with linear alkylgroups are more easily degraded. From these data, it can be concludedthat all malate surfactants are easily biodegraded, with the exceptionof di(4-methyl-2-pentyl)malate. In addition, since all malates degradedto a significant extent in 28 days, these compounds are not expected topersist or bioaccumulate in the natural environment. Moreover, it shouldbe emphasized that the tests used for the materials of this inventionare very stringent biodegradation screening tests and higher degrees ofbiodegradation are likely for longer-term tests, tests usingacclimatized biomass and under the conditions of a well-maintainedwastewater treatment plant.

TABLE 3 Biodegradation Percent Percent Biodegradation BiodegradationStructure Trial at 5 days Trail at 28 days Example 31 (Example 1)

1 2 3 average  2   0^(a)   0^(a)  1 4 5 6 average 100  100  100  100 Example 32 (Example 2)

1 2 3 average 38 35 32 35 4 5 6 average 100  100  100  100  Example 33(Example 3)

1 2 3 average 16 13 14 14 4 5 6 average 100  100  100  100  Example 34(Example 4)

1 2 3 average   0^(a)  3   0^(a)  1 4 5 6 average 79 100  100  93Example 35 (Example 5)

1 2 3 average 53 47 47 49 4 5 6 average 91 88 83 87 Example 36 (Example6)

1 2 3 average 31 37 39 35 4 5 6 average 100  76 54 77 Example 37(Example 7)

1 2 3 average 26 30 30 29 4 5 6 average 88 85 86 86 Example 38 (Example8)

1 2 3 average 61 46 47 51 4 5 6 average 88 95 100  94 Example 39(Example 9)

1 2 3 average  2  2   0^(a)  2 4 5 6 average 29 29 59 39 Example 40(Example 10)

1 2 3 average 44 — — 44 4 5 6 average 79 91 96 89 Example 41glucose/glutamic 1 71 4 94 acid control 2 65 5 94 3 67 6 100  average 68average 96 ^(a)Biodegradation that was below the detection limit of thetest (<24 mg/L or <8 % biodegradation)

The ability of a surfactant in aqueous systems to reduce surface tensionunder both equilibrium and dynamic conditions is of great importance inthe performance of waterbased coatings, inks, adhesives, fountainsolutions and agricultural compositions. Low equilibrium surface tensionallows the development of excellent properties subsequent toapplication. Low dynamic surface tension results in enhanced wetting andspreading under the dynamic conditions of application, resulting in moreefficient use of the formulations and fewer defects. In waterbornecoatings, inks, adhesives, fountain solutions and agriculturalcompositions, the formation of foam is generally undesirable because itcomplicates handling and can cause defects or result in inefficientapplication. Furthermore, there is substantial interest in the industryin the development of environmentally-friendly surfactants. As a result,it is essential to the invention described herein is that this newfamily of surfactants not only possess the aforementioned desiredperformance attributes but also is derived from naturally occurringcompounds or their synthetic equivalents and possess favorableenvironmental characteristics, such as facile biodegradation. Moreover,it is desired that this novel family of surfactants which exhibit goodequilibrium and dynamic surface tension properties, are low-foaming, arealso low viscosity liquids to facilitate handling, and have low colorand low odor characteristics.

Although dialkylmalates have been studied in numerous applications,their role appears to have not been to as surfactants themselves. Inparticular, surfactancy by relatively short chain dialkylmalates is notapparent from the prior art. In fact, there are not many examples ofshort-chain dialkylmalates in aqueous media. A property which isparticularly not apparent from the prior art is the outstanding dynamicproperties shown by dialkylmalates in reducing the surface tension ofaqueous mixtures under conditions of high surface creation rates andthat this performance would be particularly good for malic acid esterscontaining C3 to C5 alkyl groups and especially good for malic acidesters containing C4 alkyl groups. Moreover, it is not expected from theprior art that terminal branching in the alkyl groups would increaseboth the efficiency and effectiveness of the surfactant and thatdialkylmalates prepared from primary alcohols would perform better thanthose prepared from secondary alcohols, with isobutyl alkyl groupsresulting the optimum combination of such properties.

In order to obtain satisfactory performance under high speed applicationconditions, surfactants that exhibit both reduction in surface tensionunder dynamic conditions and low foam are essential. Unexpectedly, thesemalic acid ester surfactants are low foaming. In addition, many of thesedialkylmalates biodegrade easily. This property, in combination withunique dynamic surface tension reducing capabilities, low foam anddesirable physical characteristics, such as low color, low odor and lowviscosity, afford a novel class of surfactants which are particularlysuited for a variety of waterborne compositions including coatings,inks, adhesives, fountain solutions and agricultural compositions.

Statement of Industrial Application

The invention provides compositions suitable for reducing theequilibrium and dynamic surface tension in water-based coating, ink,adhesive, fountain solution and agricultural compositions.

We claim:
 1. An aqueous organic coating composition comprising in anaqueous medium 30 to 80 wt % of a coating composition which comprisesthe following components 0 to 50 wt % pigment dispersant, grind resin ormixtures thereof; 0 to 80 wt % coloring pigment, extender pigment,anti-corrosive pigment, other pigment types or mixtures thereof; 5 to99.9 wt % water-borne, water-dispersible or water-soluble resin ormixtures thereof; 0 to 30 wt % slip additive, antimicrobial agent,processing aid, defoamer or mixtures thereof; 0 to 50 wt % coalescing orother solvent; 0.01 to 10 wt % surfactant, wetting agent, flow andleveling agents or mixtures thereof; and 0.01 to 20 wt % malate havingthe structure:

where R₁ and R₂ are a C3 to C6 alkyl group.
 2. An aqueous inkcomposition comprising in an aqueous medium 20 to 60 wt % of an inkcomposition which comprises the following components 1 to 50 wt %pigment; 0 to 50 wt % pigment dispersant, grind resin or mixturesthereof; 0 to 50 wt % clay base in a resin solution vehicle; 5 to 99 wt% water-borne, water-dispersible or water-soluble resin or mixturesthereof; 0 to 30 wt % coalescing or other solvent; 0.01 to 10 wt %processing aid, defoamer, solubilizing agent or mixtures thereof; 0.01to 10 wt % surfactant, wetting agent or mixtures thereof; and 0.01 to 20wt % malate diester having the structure;

where R1 and R2 are a C3 to C6 alkyl group.
 3. An aqueous agriculturalcomposition comprising in an aqueous medium 0.01 to 80 wt % of anagricultural composition which comprises the following components 0.1 to50 wt % a herbicide, insecticide, plant growth modifying agent ormixtures thereof; 0.01 to 10 wt % surfactant; 0 to 5 wt % dye; 0 to 20wt % thickener, stabilizer, co-surfactant, gel inhibitor, defoamingagent or mixtures thereof, 0 to 25 wt % antifreeze; and 0.01 to 50 wt %malate diester having the structure:

where R1 and R2 are a C3 to C6 alkyl group.
 4. An aqueous fountainsolution composition comprising the following components 0.05 to 10 wt %film formable, water soluble macromolecule; 1 to 25 wt % alcohol,glycol, or polyol with 2-12 carbon atoms which is water soluble or canbe made water soluble; 0.01 to 20 wt % water soluble organic acid,inorganic acid, or a salt thereof; 30 to 70 wt % water; and 0.01 to 5 wt% malate diester having the structure:

where R1 and R2 are a C3 to C6 alkyl group.
 5. An aqueous adhesivecomposition comprising in an aqueous medium 30 to 65 wt % of an adhesivecomposition which comprises the following components 50 to 99 wt %polymeric resin; 0 to 50 wt % tackifier; 0 to 0.5 wt % defoamer; and 0.5to 2 wt % malate diester having the structure:

where R1 and R2 are a C3 to C6 alkyl group.